by Joseph Goguen

Natural language is often criticised, e.g., by advocates of formal methods,
for its informality, ambiguity, and lack of explicit structure1. But who would deny the value of talking,
listening, reading, and writing? Clearly natural language is a very useful
and powerful way to communicate, and it is obviously far more widely used than
any formal alternative.

There is also growing evidence that natural language is far more structured
than most people realize, and in particular, that discourse structure
(i.e., the structure of multi sentence units) carries much important
information. For example, work by Abbott [1] and others
shows that the nouns and verbs used in stating requirements can provide
important clues to an object oriented design for the system. In particular,
the nouns give clues about classes and their attributes, and the verbs give
clues about methods. Syntactic structure can also indicate relationships of
inheritance and clustering. However, one cannot expect to find mechanical
algorithms that will do such analyses with consistent reliability, in part
because of the enormous importance of context for determining meaning.

One of the most powerful types of discourse in natural language is story
telling, i.e., narrative. The classic studies of William Labov [5] concern oral narratives of personal experience,
where the narrator is an agent in the story. According to the principle of
accountability, a member of some group who tells an informal story must
establish to the audience the relevance of the actions reported. The most
typical way to accomplish accountability is to include specific evaluative
material within the body of the story that relates the narrative
material to shared social values.

We may briefly summarize the discourse structure of narratives of personal
experience as follows:

There is an optional orientation section, which gives information
about the time, place, characters, etc. in what will follow.

The main body of the narrative consists of a sequence of narrative
clauses describing the events of the story; by a default convention,
called the narrative presupposition, these are taken to occur in the
same order that they appear in the story. The narrative clauses are usually
in the past tense.

The narrative clauses are interwoven with evaluative material,
which provides interpretative or evaluative information, i.e., which relates
the events to the narrator's value system, which by default is presumed to be
shared with the audience. Evaluative material often appears in separate
clauses, but it may also take the form of repeated words, unusual syntactic
or lexical choice, etc.

There is an optional closing section, which summarizes the story,
or perhaps gives a moral.

This structure is the result of work by William Labov [5], as refined by Charlotte Linde [6], and lies
in the tradition called socio-linguistics; it is a relatively precise
framework, especially in comparison with traditions such as literary theory
and post-structuralism. Note that the default narrative presupposition can be
overridden by providing explicit markers of alternative intentions, such as
flashbacks and flashforwards. Moreover, longer narratives may involve
alternative perspectives, alternative interpretations, etc. However, such
narratives will still be composed of subsequences that conform to the above
structure.

It may be surprising that values are an integral part of the internal
structure of stories, rather than being confined to the optional summary
``moral'' at the end. But in fact, naturally occurring stories embody
evaluative material in many ways. Values in narrative may appear relatively
explicitly, as justifications for the narrator's choice of what to tell, or a
character's choice of what to do; they may also appear in a more implicit way,
in certain patterns, such as repetition, unusual or strong lexical items, and
unusual syntax. Evaluative material plays the crucial role of connecting the
events reported to the values shared by the social group within which the
story is being told. Note that the narrative presupposition, that the order
of narrative clauses is the order of the events that they report, unless some
trouble is taken to indicate otherwise, is a convention, and
not a necessity; for example, Becker [2] shows
that in Balinese narratives, if no special care is taken then the events
reported in a sequence of narrative clauses are taken as occurring
simultaneously rather than sequentially (a computer scientist might
say that the default connective for a narrative sequence in English is
sequential composition, ``;'', whereas in Balinese it is parallel
composition, ``||'').

To better explain and illustrate these ideas, let us analyse a simple
story. The nursery rhyme given below is strictly speaking not a naturally
occurring spontaneous story, nor a narrative of personal experience, in the
sense of Labov [5]. However, it is often read, or repeated
from memory with minor variations, to children in natural social settings, and
thus an analysis of the values in it should tell us something about what our
society teaches its children. The analysis will be somewhat sketchy, omitting
many details of argument, because to include them all would be very tedious2. Here is the text:

Jack and Jill went up the hill
to fetch a pail of water;
Jack fell down and broke his crown,
and Jill came tumbling after.
Up Jack got, and home did trot,
as fast as he could caper,
Jill put him to bed and plastered his head
with vinegar and brown paper.

(The second verse is one among several variations; see Opie [8] for this and other background information.) The first line of
the first verse can be seen as both an abbreviated orientation section, and as
an initial narrative clause, since the characters, Jack and Jill, and the
place, "the hill," are introduced, as well as an action, "went up," which is
in the narrative past tense. The second line is an evaluative clause, giving
a reason for the action of the first clause. The third and fourth lines give
further narrative clauses (there are two in the third line). The narrative
presupposition gives the order of the events reported: first Jack and Jill
went up the hill, then Jack fell down, then he broke his crown, and then Jill
came tumbling after.

Since we know that ordering is significant in English narratives, it is
interesting to notice that Jack always comes before Jill. As far as the
semantics is concerned, this ordering would not matter in the first line, but
because it is part of a general pattern, we can consider it to be an
evaluative feature of the narrative. Note the delicacy, and not quite
water-tight quality of this argument; this is entirely typical, since rigorous
proofs are impossible in this area. It is not so much a matter of
proving something, or extracting the truth, as it is of
uncovering some resonance within the text. Any such analysis is contingent,
local and open; moreover, it is best done in a group, so that the analyst is
accountable to other analysts, in which case the analysis itself becomes
emergent and embodied at that level. Nonetheless, any such interpretation can
be considered to be some part of the meaning of the text; of course, each
interpretation will seem more cogent to some analysts and groups than others,
and some may seem dubious to most.

What can we conclude about this story? I think we may conclude that water
is important to this (somewhat mythical) culture, and that males are more
important than females in it. This need not be the end of the analysis: one
can get some further results by using the causal presupposition, which
says that, other things being equal, given clauses in the order A, B we may
assume that A causes B. (For example, ``You touch that, you gonna die.'') I
encourage readers to follow up this remark as an exercise in further analysis
of the nursery rhyme text.

Analyses like those sketched above can be useful in a wide variety of
personal and business situations. For example, we may want to know what are
the implicit values in a threatening document that we have received from a
colleague, or we may want a deeper insight into what motivates our boss, or a
friend.

Research by Goguen and Linde [4], [7]
has shown that plans, explanations, directions, and other everyday types of
discourse have a high level structure that relates directly to their social
and semantic domains. These structures are called discourse types, and
they can be described very precisely by grammars, in much the same way as is
traditional in linguistics for structure at the sentential level. The
structure of narrative sketched above is a good example, in fact, the original
example that inspired the others. Just to give a taste, the default
presupposition for clauses in the reasoning discourse type is logical
consequence, in the direction indicated by the English word "because."

Joseph Goguen. Requirements Engineering
as the Reconciliation of Social and Technical Issues. In Requirements
Engineering: Social and Technical Issues, edited with Marina Jirotka,
Academic Press, 1994, pages 165-199.

* Paragraphs 2 through 9 were extracted from [3] and then edited. The rest of this essay is new; it is
aimed at computer scientists, rather than linguists or any kind of social
scientist.

1. Ambiguity and informality can actually be
advantagous features of natural language. For example, they can facilitate
the gradual evolution of requirements for complex systems, without forcing too
early a resolution of conflicts and ambiguities that are inherent in the
initial situation; it is important not to prejudge the many tradeoffs that
will have to be explored later on, such as cost versus almost everything else,
including speed and functionality [3]. Also, natural
language can permit the resolution of conflicts through the careful
construction of deliberate ambiguities; for example, this is rather common in
large government financed projects, as well as in diplomacy. One current
example is the proposal to proclaim Jerusalem to be under the sovereignty of
God, rather than that of either Israel of the Palestinian Authority.